The process of healing and repair starts right from the time of injury. Often, there is ongoing inflammation as well.This makes sense as the key players are often inflammatory cells, as well as the substances they release.

If you recall, in chronic inflammation, the definition also includes ongoing repair.

Recap: “Chronic inflammation is inflammation of prolonged duration (weeks or months) in which inflammation, tissue injury and attempts at repair co-exist, in varying combinations.”

The main events in healing and repair are Cell Regeneration and Fibrous Repair

The specific processes involved include:

i. Haemostasis: Activation of coagulation pathways to form a blood clot.This stops bleeding and also acts as a scaffold for the migration of cells that are involved in the regeneration and repair process..

ii. Epithelial cell regeneration / proliferation: Surface lining epithelial cells to replace epithelial layer. Fibroblasts / myofibroblasts, endothelial cells and stromal stem cells to form fibrous scar tissue.

iii. Angiogenesis / Granulation tissue: 

Angiogenesis – Formation of new blood vssels.

Granulation tissue  - Newly formed small blood vessels and fibroblasts, occurring in the early phase of repair (24-72h). There is often accompanying oedema. Gross appearance – pink, soft, granular on the wound surface.

ivi. Myofibroblast / wound contraction: Reduction of wound urface area (closure of gap)by the action of myofibfoblasts.

v. Collagen (ECM) synthesis and remodelling: Deposition of collagen and linking of collagen fibers.

1. Cells – Macrophages, lymphocytes, platelets, endothelial cells, fibroblasts etc.

2. Cytokines, Growth factors, Enzymes - some of these are mentioned in mindmaps 2 and 3.

3. Extracellular matrix:

• Structural proteins (eg. collagens)
• Adhesive glycoproteins (eg. cadherins)
• Proteoglycans and Hyaluronan

This is only an introduction to the key players. Read your textbook.lecture notes and make up a table of the key players and their main functions.